Embodiments of inventive concept relate to an analog-digital converting scheme, and more particularly, to a two-step analog-digital converting circuit, operating method thereof, and devices including the same.
An image sensor captures images using light reaction characteristics of a semiconductor. A complementary metal-oxide semiconductor (CMOS) image sensor, in particular, consumes less power than a charge coupled device (CCD) image sensor, and is widely used in portable phones, digital cameras, and the like, in accordance with development of CMOS technology.
The CMOS image sensor includes an analog-digital converter (ADC) for processing a pixel signal output from a pixel. The ADC used herein is a single slope ADC. The single-slope ADC converts a pixel signal into a digital signal using a counter. Therefore, the higher the bit resolution, the more power is consumed by the single-slope ADC. A count clock signal, which has a higher frequency, is required to increase converting operation speed of the single-slope ADC, thus increasing power consumption of the single-slope ADC.